A captivating thriller: 'Prisoners' engrosses audience, but drags on too long

"Prisoners" is a mystery told with such skill that just when you think you've figured it out, it finds new blind alleys for us to visit.

Well-cast and wonderfully acted, it's a child kidnapping thriller with sorrow, intrigue, psychology and just enough urgency to suck us in. Then it almost outsmarts itself with a draggy, "let's explain it all" third act that undercuts the big theme it wants us to ponder.

The grey skies of a Pennsylvania winter set the tone. The Dovers and the Birches are friends and neighbors. Remodeling contractor Keller Dover (Hugh Jackman) is man's man, something of a survivalist, teaching his son Ralph to hunt and "be ready" in case things get hairy and society starts to break down. With his wife, Grace (Maria Bello), he's raising a teen (Dylan Minnette) and a tyke, Anna (Erin Gerasimovich), in their middle-class subdivison.

The Birches (Viola Davis, Terrence Howard) have the Dovers over for Thanksgiving, so that tiny Joy (Kyla Drew Simmons) can play with her best pal, Anna. The teens, Ralph and Eliza Birch (Zoe Borde), are in charge of the little girls, who are young and trusting and prone to not see the risks in playing on that strange, ratty old RV parked down the street.

The girls disappear, and as their mothers stumble into shock and the men, especially Keller, hurl themselves into a frantic search, a loner police detective (Jake Gyllenhaal) takes charge of the case.

Keller knows too many statistics about how long such abducted kids survive, the increasingly long odds facing them, to control his temper. Detective Loki (I know, right?), chewing on a matchstick, blinking hard every time he takes some fresh detail in, is sure to get under his skin.

They nab a suspect, and it's easy to mark Alex Jones (Paul Dano) as the perpetrator. Creepy, uncommunicative, a veritable thick-glasses cliche of a pervert. Keller, a paragon of moral certitude, is sure of it. And when the cops can't make a case, he takes matters into his own hands. That's when "Prisoners" turns truly disturbing, grisly and morally ambiguous. Here is "enhanced interrogation" laid bare, showing both its cost to the victims of it and those who carry it out.

The two girls are merely the first prisoners. Soon, everyone is trapped - parents, siblings, the cops, the suspect, the suspect's aunt (Melissa Leo).

"Prisoners" gives everybody a history. Add to that the dragnet that has Loki visiting every sex offender in the area, with assorted deviants (including a defrocked priest) either ruled out or added to the mystery.

But despite the occasional chase or chilling moment during surveillance, "Prisoners" loses urgency as it drags on. The dread and weight of "The Lovely Bones" and "The Vanishing" hang over it, augmented by chilly scenes of winter. But Villeneuve loses himself in that and his "they're all prisoners" thread in a third act that goes on far too long and explains far too much.

"Prisoners" is never less than engrossing. It'll keep you guessing. It's just too bad that the last 30 minutes make us feel like the prisoners here.

Rated R for disturbing violent content including torture, and language throughout